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Alloy joining

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john brown 1703/05/2020 12:58:30
114 forum posts
3 photos

Needed to join some funny shape alloy bits together, so used some rods that you use a blow torch to weld them together,well am so pleased with it ,it opens up a good way to join alloy parts together,l even had a go with some crappy cast alloy ,for the test used 6 mm and some 10 mm plate , and had to beat the hell out of them to break them very pleased .


Bo'sun03/05/2020 15:42:30
141 forum posts

Afternoon John,

Sounds useful. Can you add some details about the rods and the process?

not done it yet03/05/2020 16:10:18
4639 forum posts
16 photos

Not quite welding, but easy and it does a good job. Generally comes as thick wire rather than rods. Just melt the filler and then may need to scratch the surface(s) with stainless steel brush/pointer and watch as the metals ‘weld’.

I reckon the material is basically ‘Birmabrite’ - the material used for early Landrover panels.

I bought some at the Midlands show a couple of years ago. The exhibitor does demos every show. Don’t know what other shows this guy exhibits at, but likely keeps him busy (but not currently!).

I might need some more next show....

mark costello 103/05/2020 17:27:08
589 forum posts
12 photos

I also use something similar over here, works well, but 2 caveats, I had to plug a hole that had wandered into another hole. When the repair metal melted it seemed to concentrate the heat into the main part and it ran into the adjacent hole requiring a steel rod inserted to keep the other hole open. This was using a propane torch so not enough imput to melt a piece of Aluminum 7/8"x1"x 4" long. Once something is repaired with this rod it evedentally cannot be TIG welded.

john brown 1703/05/2020 17:44:14
114 forum posts
3 photos

Yes not done it yet about sums it up ,my welds are techno weld rods ,just use a stainless brush to clean the area and away you go,just heat up the parts to be joined and keep rubbing the rod along till it starts to stick a bit then heat a bit more and run the rod along ,but keep the flame away from the rod ,the heat in the alloy makes it work not the torch,like l said in my first post l took a big hammer to the test weld before it would break ,have also been testing with 1mm thick plate just using a small blow torch and it works great plus it drills and taps ok so one can fill holes etc file flat and away you go,after playing with test bits then the job l needed done still have about half of one of the rods left,you get five rods and a s/s wire brush for about £20 to the door, so well worth it to have in the work shop,it even worked well repairing round a bit of old die casting just to se if it would and again great,makes a change to se what it says on the box indeed works.


AJW03/05/2020 18:09:03
289 forum posts
117 photos

I last saw this on demo at AllyPally and it looked fantastic, the guy even let me have a go, very impressed but I remember it cost about £40 do a 3ft length - the roll it was on must have cost a fortune.


Stuart Smith 503/05/2020 18:41:45
95 forum posts
25 photos

‘Mr Factotum’ on youtube has been doing a series of videos of his Metre Maid loco build.

The latest one shows him fabricating the saddle from aluminium sheet and ‘Lumi-welding’ it together.


old mart03/05/2020 19:25:13
1753 forum posts
138 photos

I remember using something with a name like "lumiweld" to use on aluminium back in the 60's or 70's, it worked well.

Jouke van der Veen03/05/2020 19:34:54
52 forum posts
7 photos

Some years ago I “brazed” some Al test samples together. Some bonds were very good, others were just rubbish.

I did this with pure Zn because I found that mostly Zn with a few % of Al is used for this with a melting point around 400C. So I had the feeling that it should also work with pure Zn and it did. I soldered in a torch flame with a bad temperature control. When it got to hot you had a real “melt-down”.

Later on I had some Zn soldering wire wit different concentrations of Al an fluoride flux available.

These alloys are also used as a filler metal for damaged Al castings.

I never repaired the real part (a broken guidance of a band sawing machine).

Clive Foster03/05/2020 19:41:21
2204 forum posts
73 photos

Lumiweld was what I used back in the day. It was the common trade name back in the 1970's and 80's. Techno weld seems to have come along later.

Its all essentially the same stuff.

One of the constituents of the stick alloy acts to depress the melting point of the aluminium locally so it fuses with the rod when the aluminium is at the rod melting temperature. Need to get through the oxide coating for it to work. Hence the stainless steel scratcher. Fortunately once an initial fusion is made it runs along under the oxide coating and lifts it off fairly well.

I found it needed parctice and that different alloys behaved a little differently.


Martin Connelly03/05/2020 20:00:12
1369 forum posts
159 photos

Various types of brass, various types of bronze, various types of steel are alloys. Alloy does not specify a material.

Martin C

not done it yet03/05/2020 20:07:37
4639 forum posts
16 photos

Soon after I got mine (a good length measured off by ‘arm’s length’ I was at Arceuro and asked if they had a stainless steel scribe (as a ‘scratcher). They didn’t but Ian (I think) quietly handed me a cheap freebie stainless 150mm ruler for the purpose of ‘scratching’. Perfectly adequate for the job but don’t actually used it for that, as I found a piece of stainless rod and ground a spike on it.

My little metal bender will not cope (easily) with anything above about 4mm thick - if more than about 20mm wide, so the ‘welding kit’ sometimes comes in handy for larger sections of aluminium and often useful because the ‘bend’ doesn’t have a curvature (so cut to length without having to calculate the extra for a bend)🙂. Nothing has broken yet.🤞🏻

Nick Clarke 303/05/2020 21:23:06
760 forum posts
25 photos

Machine Mart sell a similar kit - but that has a COSHH safety sheet that says the makeup is mainly Zinc with small amounts of aluminium and copper.

Emgee03/05/2020 23:07:28
1485 forum posts
217 photos

Before Lumiweld was available in the UK I used a Camping Gaz product, the kit contained rods, stainless wire brush, piece of 2mm stianless rod and a small clear container of white powder that you mixed with water and applied it to the ally after cleaning the area using the wire brush.
When heat was applied and the parent metal reached the correct temperature for soldering the flux turned black so the filler rod was applied and the stainless wire pushed into the bubble of molten rod to scratch the surface working it along the joint.
I had some success but also some jobs that ended in disaster, the best results were obtained when joining like materials, thickness and grade. I found that on larger parts a second heat source was beneficial to keep the job nearly up to usable temperature.
The guys that demonstrate the product are very skilled which makes the product seem easier to use than IMO is the case, for me the product is a bit hit and miss.


Danny M2Z04/05/2020 04:30:35
849 forum posts
282 photos

Many years ago i offered bed and breakfast to the late Mr. Brian Winch who was visiting Albury for the annual model floatplane festival.

As penance he was required to demonstrate using Lumiweld after he wrote a glowing report of it's usefulness in the Australian Airborne model magazine.

I invited a mate along and at midnight Mr.Winch showed us how to repair a broken out engine lug on a DC Dart engine usind my jeweller's propane torch.

As a reward at dawn I managed to catch a nice trout for his breakfast and soon discovered that he was an accomplished cook.

R.I.P. Brian.

* Danny M *

Bo'sun04/05/2020 07:15:07
141 forum posts

Any idea why it needs a "stainless steel" brush or scratcher? Why not an ordinary wire brush?

not done it yet04/05/2020 07:19:07
4639 forum posts
16 photos

Presumably practical experience has shown an advantage? Reactivity ,or non-reactivity, is the reason at a guess.

I would just say ‘ignore it at your peril’.

shaun meakin 104/05/2020 09:52:50
42 forum posts
1 photos

The product described as being demonstrated at Ali Pally is what we call Technoweld. We supply a small pack of 5 x 200mm rods (so 1 metre) which comes with a scratch stick and a full set of instructions. On the website this is £16.20 but this week only for telephone orders CuP Alloys are offering Discounted Doncaster Exhibition prices, in this case £15.00. Please note this is telelphone orders only and is valid 4 - 8th May inclusive.

Kiwi Bloke04/05/2020 12:22:58
424 forum posts
1 photos

SIF 555 'self-fluxing alloy solder' appears to be the same stuff - but far cheaper than some suppliers (because less BS content?)...

Zn 93%, Al 4%, Cu 3%, melting point 380C.

Edited By Kiwi Bloke on 04/05/2020 12:23:43

Bazyle04/05/2020 13:21:55
5215 forum posts
201 photos

I think a non stainless brush will contaminate the joint with specs of rust and iron oxide. The addition of alloying aluminium will slightly lower the melting point (google zinc aluminium phase diagram). Copper would normally raise it but may not here and must have some other purpose. Unfortunately the copper may promote corrosion as it does in Dural.

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